Flame retardant vinyl chloride polymers containing zinc zirconate

ABSTRACT

Vinyl chloride polymers are compounded with zinc zirconate to provide improved flame resistance and reduce smoke production.

United States Patent 1 1 Dickens, Jr.

[451 Apr. 29, 1975 FLAME RETARDANT VINYL CHLORIDE POLYMERS CONTAININGZINC ZIRCONATE Appl. No.: 493,723

Inventor:

Assignee:

US. Cl 260/45.75 W; 260/4575 F;

260/4249 Int. Cl. C08f 45/56 Field of Search 260/4575 W; 106/15 FP;

References Cited UNITED STATES PATENTS Cox 260/4575 Riches 117/138Elliott..... 260/45.75 Scullin 260/4575 Yates 260/4249 PrimaryExaminerV. P. Hoke Attorney, Agent, or Firm-J. Hughes Powell, Jr.

ABSTRACT Vinyl chloride polymers are compounded with zinc zirconate toprovide improved flame resistance and reduce smoke production.

4 Claims, No Drawings FLAME RETARDANT VINYL CHLORIDE POLYMERS CONTAININGZINC ZIRCONATE BACKGROUND OF THE INVENTION Presently there is a pressingneed for improved plastic products which are safer in firesituations,.even for vinyl chloride polymers which generally areconsidered to be flame resistant. While rigid vinyl chloride productshave many structural applications useful in build- 2 group such asvinylidene chloride, alkyl acrylates and methacrylates wherein the alkylgroup contains one to 10 carbon atoms, acrylic acids, amides andnitriles thereof such as acrylic acid, ethacrylic acid, acrylam- 5 ides,N-methylol methacrylamide, acrylonitrile, methacrylonitrile and thelike, alphaolefins containing two to six carbon atoms such as ethyleneand propylene, vinyl esters such as vinyl acetate. vinyl butyrate, vinylbenzoate, vinyl aromatics such as styrene, chlorostyrene, ethyl styrene,vinyl naphthalene, vinyl alkyl ethers, vinyl ketones, chlorinated vinylchloride polymers; and blends of vinyl chloride polymers with otherpolymers, both plastics and elastomers, for example, with ABS resins,with l to 40 percent of copolymers of styrene and acrylonitrile orstyrene and methyl methacrylate wherein styrene is the major component,

elastomers containing about equal amounts of styrene and acrylonitrilewith butadiene, polyurethanes, nitrile "elastomers, both liquid andsolid containing from about 15 to 40 percent acrylonitrile with theremainder butadiene, polyolefins and the like. These vinyl chlorideflame spread. While a number of materials have been proposed and used invinyl chloride for this purpose,

very few have been found to be completely satisfactory. Many are notcompatible or readily mixed with vinyl chloride polymers, many arecolored or form colored products in vinyl chloride polymer compositionsand many have adverse effects on the physical properties of vinylchloride polymers.

SUMMARY OF THE INVENTION Zinc zirconate is a very effective fire andsmoke retardant in vinyl chloride polymer compositions even in lowconcentrations. The zinc zirconate is compatible and easily mixed withvinyl chloride polymers in both rigid and flexible forms, has lowtinting power, does not form objectionable color products in vinylchloride polymers and has no adverse effects on the physical propertiesor processing of compounds containing it.

DETAILED DESCRIPTION The zinc zirconate is normally used in powder form.

in amounts greater than about 0.01 part per 100 weight parts of vinylchloride polymer, more preferably from about 0.1 to about to weightparts per 100 weight parts of vinyl chloride polymer. From about 0.25 toabout 3 weight parts is a very practical range providing -a good balanceof desirable properties in the compounds. The zinc zirconate is readilymixed with the vinyl chloride polymers in powder form as is any otherpowder ingredient mixed with vinyl chloride polymers as is well known tothose skilled in the art.

The vinyl chloride polymers include those vinyl chloride polymers thatare homopolymers, that is, polyvinyl chloride, as well as thosecopolymers containing vinyl chloride and up to about 50 percent, moreusually about percent by weight of at least one other vinylidene monomercontaining at least one terminal polymers normally are high molecularweight polymers having a specific viscosity greater than 0.4 measured asa 0.4 percent solution in nitrobenzene.

The vinyl chloride polymers will be mixed with standard compoundingingredients known to those skilled in the art, plasticizers, lubricants,stabilizers, fillers, colorants, processing aids, other flame and smokeretardants, and the like. While these compounds are most effective invinyl chloride polymers substantially free of plasticizers subject toburning, they provide improved compositions as to flame propagation andsmoke when plasticizers are present.

In the following Examples, there is reported the oxygen index, OI, a Dsmoke rating, and D,,,, a maximum optical density observed with avertical light path in the National Bureau of Smoke Chamber (NBS). Theoxygen index is determined in accordance with ASTM D2863 test method andD' smoke number measured when this apparatus is modified by the meansdescribed by Dipietro et al., Journal of Flame and Flammability, Volume2, Page 36, 197 l i.e., the optical density of the smoke generated whenthe sample is burning at the rate of 0.6 gram/minute; The NBS smokechamber and its use are described by Gross et al. in fire test methodsASTM STP 422, 1967, Pages 166-206. The NBS D smoke numbers reported arein the flaming mode.

EXAMPLE I A vinyl chloride polymer compound was prepared by mixingweight parts of polyvinyl chloride, Geon x233, specific viscosity of0.38 0.42 percent in nitrobenzene at 30C., with 2 weight parts ofpolyethylene having a specificgravity of 0.924 g/cc and melt index of 5g/ 10 minutes, and the amounts of zinc compound shown in the data tablebelow. The ingredients were all dry blended, milled at 330F. for 5minutes, press molded at 350F. for 8 minutes at 320F. 6 X 0.25 X 0.075inch test samples were used for the oxygen Index and SmokeOI. 2 /8 X 2 X0.05 inch test samples were used for the NBS smoke chamber and the chartest was on A X A X 0.075 inch or dry pressed A X 5 X 0.280 inchpellets. A one minute burn was used.

TABLE I Zinc Salt in Oxygen 7c (phr) Recipe Index D'., D,,, Char" TC"None 42 550 630 2 5 Zn ZrO 1/2) .24 49 160 14.8 34

(2) .95 60 140 378 16.5 37 zn P O, (1/2) .22 38 755 2.7 6

(2) .84 43 685 5.2 12 ZnTiO (1/2) .18 66 145 381:45 13.2 30

(a) D' is the smoke rating for the Smoke-O1 test.

(h) D,,, is the smoke rating for the NBS Smoke Chamber test. All numbersare based on an average of duplicate runs. Sample thickness wasnormalized to 50 mils.

(cl '4 Char M,-M,/Ni X 100. where M,= initial wt.. M,= final wt. Sampleswere exposed to a propane torch for 1.0 minute. Sample geometry was 1/4"X 3.4" X 0.075". Average of two runs.

(d) '/1 TC Z of theoretical char '4 Char/A. where A is the maximumamount of char that can he formed and is defined by A .44/l()(l+XX/l(ll)+X. X phr additive.

(e) Pressed sample after test was black. That containing Zn ZrO wasamhcr.

In a pigmented plasticized formulation containing 34 3. A composition ofclaim 1 wherein the vinyl chlopercent of B SO pigment and 18 percent ofdioctyl ride polymer contains up to about 50 percent by weight phthalateplasticizer with 2 parts of zinc zirconate there 20 of at least onevinylidene compound copolymerized is less smoke produced as compared tothe control. therewith having a terminal 1 claim: 1. A compositioncomprising a vinyl chloride poly- CH =C mer and zinc zirconate in anamount of from about group. 0.01 to about 10 weight parts per 100 weightparts of 4. A composition of claim 2 wherein there 15 0.75 to vinylchloride polymer. 3 parts of zinc zirconate.

2. A composition of claim 1 wherein the vinyl chloride polymer ispoly(vinyl chloride).

1. A COMPOSITION COMPRISING A VINYL CHLORIDE POLYMER AND ZINC ZIRCONATEIN AN AMOUNT OF FROM ABOUT 0.01 TO ABOUT 10 WEIGHT PARTS PER 100 WEIGHTPARTS OF VINYL CHLORIDE POLYMER.
 2. A composition of claim 1 wherein thevinyl chloride polymer is poly(vinyl chloride).
 3. A composition ofclaim 1 wherein the vinyl chloride polymer contains up to about 50percent by weight of at least one vinylidene compound copolymerizedtherewith having a terminal
 4. A composition of claim 2 wherein there is0.75 to 3 parts of zinc zirconate.